WO2023179250A1 - 一种铁电材料、铁电存储单元、存储器及电子设备 - Google Patents

一种铁电材料、铁电存储单元、存储器及电子设备 Download PDF

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WO2023179250A1
WO2023179250A1 PCT/CN2023/076001 CN2023076001W WO2023179250A1 WO 2023179250 A1 WO2023179250 A1 WO 2023179250A1 CN 2023076001 W CN2023076001 W CN 2023076001W WO 2023179250 A1 WO2023179250 A1 WO 2023179250A1
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ferroelectric
electrode
oxide
layer
material layer
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PCT/CN2023/076001
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French (fr)
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谭万良
李宇星
陈明凤
许俊豪
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华为技术有限公司
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L28/00—Passive two-terminal components without a potential-jump or surface barrier for integrated circuits; Details thereof; Multistep manufacturing processes therefor
    • H01L28/40—Capacitors
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10B—ELECTRONIC MEMORY DEVICES
    • H10B53/00—Ferroelectric RAM [FeRAM] devices comprising ferroelectric memory capacitors
    • H10B53/30—Ferroelectric RAM [FeRAM] devices comprising ferroelectric memory capacitors characterised by the memory core region
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10B—ELECTRONIC MEMORY DEVICES
    • H10B53/00—Ferroelectric RAM [FeRAM] devices comprising ferroelectric memory capacitors
    • H10B53/40—Ferroelectric RAM [FeRAM] devices comprising ferroelectric memory capacitors characterised by the peripheral circuit region
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N97/00—Electric solid-state thin-film or thick-film devices, not otherwise provided for

Definitions

  • the present application relates to the field of storage technology, and in particular to a ferroelectric material, a ferroelectric memory unit, a memory and an electronic device.
  • the memory in the computer can be divided into memory that frequently exchanges data with the computing unit (such as dynamic random access memory (DRAM)) and external storage that is far away from the computing unit (such as NAND flash memory).
  • DRAM dynamic random access memory
  • NAND flash memory NAND flash memory
  • DRAM has the characteristics of high-speed reading and writing, but it is volatile and requires frequent refreshing and writing to maintain data.
  • NAND flash memory is non-volatile, its read and write speeds are low and the number of times it can be erased and written is low. Therefore, under the current background, it is very urgent and crucial to find new memory devices that are non-volatile, have high read and write speeds, and have low power consumption.
  • Ferroelectric Random Access Memory is a new type of memory device. Its core is a metal-insulator-metal MIM composed of metal-ferroelectric material-metal.
  • the principle of capacitor structure is to utilize the physical phenomenon that the orientation of the electric polarization of ferroelectric materials can be changed by an external electric field.
  • ferroelectric materials are used as insulating dielectric materials for MFM capacitors, the orientation of the internal electric dipoles will be changed by the influence of the electric field, which will cause capacitor charging and discharging. Under the action of the sensing amplifier, these microphysical phenomena can be identified and thus Implement the storage state of "0" or "1".
  • FeRARM Since the polarization state of FeRAM can still be maintained after the external electric field is removed, FeRARM has non-volatile characteristics.
  • ferroelectric polarization flipping mainly comes from ion displacement. Because the flipping speed is fast and the Joule heat generated is small, it also has the advantages of fast reading and writing speed and low power consumption.
  • perovskite structures such as Pb(Zr,Ti)O 3 , a mixture of lead zirconate (PbZrO 3 ) and lead titanate (PbTiO 3 ), and barium titanate (BaTiO 3 ) are currently mainly used.
  • PbZrO 3 lead zirconate
  • PbTiO 3 lead titanate
  • BaTiO 3 barium titanate
  • Hafnium oxide (HfO 2 ) doped with zirconium (Zr) element (i.e., hafnium zirconium oxygen (HZO))-based materials have attracted widespread attention since they were discovered to have ferroelectric properties. Their ferroelectric properties originate from the oxygen ions in the crystal lattice. Directional displacement.
  • HZO-based ferroelectric materials are compatible with the Complementary Metal Oxide Semiconductor (CMOS) process and their ferroelectricity can still be maintained at 10nm, they are expected to be used in new memory devices and replace DRAM to achieve high-performance Density, high speed and low power consumption.
  • CMOS Complementary Metal Oxide Semiconductor
  • HZO-based ferroelectric materials still have several shortcomings, and further improvements are needed to enhance their durability.
  • defects at the interface between metal electrodes and ferroelectric materials such as oxygen vacancies, will lead to awakening, fatigue and fatigue in HZO-based ferroelectric materials.
  • Breakdown effect This is because the oxygen vacancies existing at the interface between the metal electrode and the ferroelectric material during the preparation process have a nailing effect on the ferroelectric domain.
  • the pinning effect suppresses the initial residual polarization intensity Pr.
  • the pinning effect of oxygen vacancies weakens as the number of flips increases, so the polarization intensity Pr gradually increases.
  • the oxygen vacancies will promote the conversion of the non-ferroelectric phase (M phase) into the ferroelectric phase (O phase), and the polarization intensity Pr will further increase.
  • the oxygen ions in HZO gradually escape and gather at the interface, causing the polarization intensity Pr to begin to decrease, which is a fatigue effect.
  • a large number of oxygen vacancies form conductive channels leading to device breakdown. Therefore, how to reduce the oxygen vacancy concentration is an urgent technical problem that those skilled in the art need to solve.
  • the present application provides a ferroelectric material, a ferroelectric memory unit, a memory and an electronic device for reducing the oxygen vacancy concentration in the ferroelectric memory unit.
  • the application provides a ferroelectric memory unit, including a first electrode and a second electrode arranged oppositely, and a ferroelectric layer located between the first electrode and the second electrode.
  • the ferroelectric layer may include a stacked arrangement.
  • the HfO 2- based ferroelectric material layer and the oxide material layer with a layered structure.
  • the layered structure of the oxide material is used to increase the lattice spacing of the oxide material layer 032, making it easier for oxygen ions to move in the material, so that oxygen ions can more easily enter the HfO 2- based ferroelectric material.
  • the ferroelectric memory unit can effectively reduce the oxygen vacancy concentration inside the ferroelectric layer by utilizing the layered structure in the ferroelectric layer, thereby reducing the possibility of oxygen vacancies accumulating to form a conductive path, and effectively regulating the ferroelectric layer. Oxygen vacancies, thereby weakening the negative effects of oxygen vacancies on awakening, fatigue and breakdown, ultimately achieving the purpose of improving the electrical performance and durability of the device.
  • HfO2- based ferroelectric materials include, but are not limited to, HfO2 materials doped with zirconium (Zr), silicon (Si), lanthanum (La), yttrium (Y), strontium (Sr), gadolinium (Gd) ) and aluminum (Al) at least one element.
  • the first electrode, the ferroelectric layer and the second electrode are stacked in a vertical direction, that is, the first electrode may be the bottom electrode and the second electrode may be the top electrode.
  • the first electrode, the ferroelectric layer and the second electrode can also be arranged side by side in the horizontal direction.
  • the first electrode, the ferroelectric layer and the second electrode can also be arranged sequentially from the inside to the outside, that is, the ferroelectric layer surrounds the first electrode.
  • the electrode design, the second electrode is arranged around the ferroelectric layer, is not limited here.
  • the stacked HfO 2 -based ferroelectric material layer and the oxide material layer with a layered structure refer to being stacked in the direction in which the first electrode points to the second electrode.
  • the first electrode points to the second electrode.
  • the direction of the electrode is the vertical direction
  • the HfO 2 -based ferroelectric material layer and the oxide material layer with a layered structure are stacked in the vertical direction.
  • the direction of the first electrode pointing to the second electrode is the horizontal direction
  • the HfO 2- based ferroelectric material layer The layers and the oxide material layers with a layered structure are stacked in the horizontal direction.
  • this application does not limit the materials of the first electrode and the second electrode.
  • They may be conductive nitride materials, such as titanium nitride (TiN), tantalum nitride (TaN), etc., or they may be metal materials, such as Tungsten (W), ruthenium (Ru), molybdenum (Mo), iridium (Ir), nickel (Ni), platinum (Pt), etc.
  • conductive metal oxide materials such as ruthenium oxide (RuO), iridium oxide ( IrO), indium tin oxide (ITO), niobate-doped strontium titanate (Nb-STO), lanthanum strontium manganese oxide ((LaSr)MnO 3 ), etc.
  • RuO ruthenium oxide
  • IrO iridium oxide
  • ITO indium tin oxide
  • Nb-STO niobate-doped strontium titanate
  • LaSr lanthanum strontium manganese oxide
  • the oxide material layer may be located between the first electrode and the HfO 2 -based ferroelectric material layer, or the oxide material layer may also be located between the second electrode and the HfO 2 -based ferroelectric material layer, or , the oxide material layer is located between the first electrode and the HfO2- based ferroelectric material layer and between the second electrode and the HfO2- based ferroelectric material layer, which is beneficial to reducing the contact between the first electrode and/or the second electrode and the iron Oxygen vacancies at the electrical layer interface.
  • the oxide material layer can also be located between the HfO2- based ferroelectric material layers, which is beneficial to reducing oxygen vacancies inside the ferroelectric layer.
  • an oxide material layer can also be provided between the HfO 2 -based ferroelectric material layers.
  • there is an oxide material layer between the first electrode and the HfO2- based ferroelectric material layer there is an oxide material layer between the second electrode and the HfO2 -based ferroelectric material layer, and between the HfO2 - based ferroelectric material layer There is a layer of oxide material in between.
  • the number of oxide material layers is not limited, and only one oxide material layer can be provided. Of course, Multiple oxide material layers may be provided. For example, two oxide material layers may be provided between the HfO 2 -based ferroelectric material layers, which are not limited here.
  • the oxide material layer with a layered structure is mainly composed of alternating single atomic layers of the oxide (AO x ) of A and perovskite structural layers containing A and B, where A and B are both metals.
  • the chemical formula of the perovskite structural layer containing A and B is mainly ABO 3 .
  • the single atomic layer of AO x is electrically neutral, it can self-adjust the ion valence state to neutralize charged defects such as space charges or oxygen vacancies.
  • this can not only reduce the pinning effect of interfacial oxygen vacancies on the ferroelectric domain and reduce the wake-up effect in the initial state of the ferroelectric memory unit; but also during the polarization flipping process, due to the oxide material
  • the oxygen ions in the layer are more active, and the oxygen vacancies are more likely to be transferred to the oxide material layer during the migration process without repeatedly migrating in the HfO2- based ferroelectric material layer to cause fatigue or even form a conductive path to cause breakdown of the entire device.
  • the Bi-containing oxide material layer can be prepared using the atomic layer deposition (ALD) method, which can be integrated into existing processes, which is beneficial to promotion and application.
  • ALD atomic layer deposition
  • AO x can be Bi 2 O 2-x , 0 ⁇ x ⁇ 2, such as Bi 2 O 2 , Bi 2 O 1.5 , Bi 2 O 1 , Bi 2 O 0.5 , etc.
  • the chemical formula of the oxide material in the oxide material layer with a layered structure may be Bi 2 WO 6 , Bi 2 Ti 3 O 12 or CaBi 4 Ti 4 O 12 , etc., which is not limited here.
  • the oxide material layer having a layered structure may include a layered oxide having a Ruddlesden-Popper phase structure.
  • layered oxides with a Ruddlesden-Popper phase structure are mainly composed of two-dimensional perovskite-like layers interlaced with cations.
  • the general formula of layered oxides with Ruddlesden-Popper phase structure is generally A n+ 1 B n The number of layers.
  • the Ruddlesden-Popper phase structure is a phase structure formed by the symbiosis of a perovskite type structure and a NaCl type structure.
  • a and B are transition metal elements, and X is an oxygen ion.
  • oxygen ions move easily between the two-dimensional perovskite-like layers.
  • transition metal ions with variable valence states when oxygen vacancies exist, they can be neutralized by regulating the valence state of the metal ions. Therefore, the layered oxide with the Ruddlesden-Popper phase structure can provide sufficient oxygen ions for the ferroelectric layer to reduce the oxygen vacancy concentration, thereby weakening the negative effects of oxygen vacancies on awakening, fatigue and breakdown, and ultimately improving the electrical performance of the device. and durability purposes.
  • A in the layered oxide having a Ruddlesden-Popper phase structure, A can be Sr, B can be Ru, and X is O.
  • the chemical formula of the oxide is Sr 2 Ru 1 O 4 .
  • the ferroelectric layer includes a HfO2- based ferroelectric material with a layered structure.
  • the HfO 2 -based ferroelectric material with a layered structure can be composed of a HfO 2 -based ferroelectric material unit cell layer and a raw material containing Bi oxide. It is composed of alternating sub-layers.
  • an atomic layer of Bi-containing oxide layer can be inserted after each layer of HfO 2 -based ferroelectric material unit cell layer is formed, thereby forming a layered structure. HfO2- based ferroelectric materials.
  • the oxygen vacancy concentration in the ferroelectric layer can be effectively reduced, thereby weakening the negative effects of oxygen vacancies on awakening, fatigue and breakdown, and ultimately achieving the purpose of improving the electrical performance and durability of the device. .
  • the Bi-containing oxide may also be doped with other metal elements, which is not limited here.
  • the Bi-containing oxide in this application is Bi 2 O 2-x , 0 ⁇ x ⁇ 2, such as Bi 2 O 2 , Bi 2 O 1.5 , Bi 2 O 1 , Bi 2 O 0.5 , etc.
  • embodiments of the present application also provide a ferroelectric material, which is mainly composed of alternately stacked unit cell layers of HfO 2 -based ferroelectric material and atomic layers containing Bi oxide.
  • a ferroelectric material which is mainly composed of alternately stacked unit cell layers of HfO 2 -based ferroelectric material and atomic layers containing Bi oxide.
  • an atomic layer of Bi-containing oxide layer can be inserted after each layer of HfO 2 -based ferroelectric material unit cell layer is formed, thereby forming a layered structure.
  • HfO2- based ferroelectric materials when preparing a HfO 2 -based ferroelectric material thin film, an atomic layer of Bi-containing oxide layer can be inserted after each layer of HfO 2 -based ferroelectric material unit cell layer is formed, thereby forming a layered structure.
  • the oxygen vacancy concentration in the ferroelectric layer 03 can be effectively reduced, thereby weakening the negative effects of oxygen vacancies on awakening, fatigue and breakdown, and ultimately improving the electrical performance and durability of the device. Purpose.
  • the Bi-containing oxide is Bi 2 O 2-x , 0 ⁇ x ⁇ 2, such as Bi 2 O 2 , Bi 2 O 1.5 , Bi 2 O 1 , Bi 2 O 0.5 , etc.
  • a Bi 2 O 2 layer is inserted into a HfO 2 -based ferroelectric material film to build an artificial layered structure.
  • an atomic layer of Bi-containing oxide layer can be inserted after each unit cell layer of HfO 2 -based ferroelectric material is formed, thereby forming an HfO 2 -based ferroelectric material with a layered structure.
  • embodiments of the present application further provide a ferroelectric memory unit, which includes a first electrode and a second electrode arranged oppositely, and a ferroelectric layer located between the first electrode and the second electrode.
  • the ferroelectric layer is mainly formed of the ferroelectric material described in the first aspect or various embodiments of the first aspect.
  • the ferroelectric layer may include alternately stacked HfO2- based ferroelectric material unit cell layers and Bi oxide-containing atomic layers.
  • alternately stacked HfO 2 -based ferroelectric material unit cell layers and Bi oxide-containing atomic layers form an HfO 2 -based ferroelectric material with a layered structure.
  • the oxygen vacancy concentration in the ferroelectric layer can be effectively reduced, thereby weakening the negative effects of oxygen vacancies on awakening, fatigue and breakdown, and ultimately improving the electrical performance and durability of the device. Purpose.
  • embodiments of the present application further provide a memory, including a control circuit and a plurality of ferroelectric memory units as described in the first aspect or various implementations of the first aspect, or including a control circuit and a plurality of ferroelectric memory units.
  • a ferroelectric memory cell as described in the third aspect or various embodiments of the third aspect.
  • the control circuit is electrically connected to each ferroelectric memory unit. Specifically, a voltage can be applied to the first electrode and the second electrode of the ferroelectric memory unit through a control circuit to control the ferroelectric memory unit to implement read and write operations.
  • an embodiment of the present application further provides an electronic device, including a processor, and a memory coupled to the processor as provided in the embodiment of the fourth aspect.
  • the electronic device may be a mobile phone, a tablet computer, a notebook computer, a wearable device, a vehicle-mounted device and other electronic devices, and of course it may also be other electronic devices, which are not limited here.
  • Figure 1 is a schematic structural diagram of a ferroelectric memory unit provided by an embodiment of the present application.
  • Figure 2 is a schematic cross-sectional structural diagram of a ferroelectric memory unit provided by an embodiment of the present application
  • FIG. 3 is a schematic cross-sectional structural diagram of another ferroelectric memory unit provided by an embodiment of the present application.
  • Figure 4 is a schematic cross-sectional structural diagram of yet another ferroelectric memory unit provided by an embodiment of the present application.
  • FIG. 5 is a schematic cross-sectional structural diagram of yet another ferroelectric memory unit provided by an embodiment of the present application.
  • FIG. 6 is a schematic cross-sectional structural diagram of yet another ferroelectric memory unit provided by an embodiment of the present application.
  • Figure 7 is a schematic cross-sectional structural diagram of yet another ferroelectric memory unit provided by an embodiment of the present application.
  • Figure 8 is a schematic diagram of the crystal structure of an oxide material with a layered structure provided by an embodiment of the present application.
  • Figure 9 is a schematic diagram of the crystal structure of another oxide material with a layered structure provided by an embodiment of the present application.
  • Figure 10 is a schematic diagram of the crystal structure of another oxide material with a layered structure provided by an embodiment of the present application.
  • Figure 11 is a schematic diagram of the crystal structure of a layered oxide with a Ruddlesden-Popper phase structure provided by an embodiment of the present application;
  • Figure 12 is a schematic diagram of the crystal structure of another layered oxide with a Ruddlesden-Popper phase structure provided by the embodiment of the present application;
  • Figure 13 is a schematic cross-sectional structural diagram of yet another ferroelectric memory unit provided by an embodiment of the present application.
  • a storage unit is the smallest unit in the memory that has data storage and reading and writing functions. It can be used to store a minimum unit of information, that is, 1 bit of data (such as 0 or 1), which is a binary bit. Through multiple storage units, multiple binary bit data can be stored. Specifically, in this embodiment of the present application, one storage unit is used to store one binary bit.
  • the memory provided by this application can be used for data storage in electronic devices such as mobile phones, tablet computers, notebook computers, wearable devices, and vehicle-mounted devices. Of course, it can also be applied to other electronic devices, which is not limited here.
  • FIG. 1 is a schematic structural diagram of a ferroelectric memory unit provided by an embodiment of the present application.
  • a ferroelectric memory cell includes a first electrode 01 and a second electrode 02 arranged oppositely, and a ferroelectric layer 03 located between the first electrode 01 and the second electrode 02 .
  • the ferroelectric layer 03 may include a stacked HfO 2 -based ferroelectric material layer 031 and an oxide material layer 032 with a layered structure.
  • the layered structure of the oxide material is used to increase the lattice spacing of the oxide material layer 032, making it easier for oxygen ions to move in the material, so that oxygen ions can more easily enter the HfO 2- based ferroelectric material.
  • the ferroelectric memory unit can effectively reduce the oxygen vacancy concentration inside the ferroelectric layer by utilizing the layered structure in the ferroelectric layer, thereby reducing the possibility of oxygen vacancies accumulating to form a conductive path, and effectively regulating the ferroelectric layer. Oxygen vacancies, thereby weakening the negative effects of oxygen vacancies on awakening, fatigue and breakdown, ultimately achieving the purpose of improving the electrical performance and durability of the device.
  • HfO2- based ferroelectric materials include, but are not limited to, HfO2 materials doped with zirconium (Zr), silicon (Si), lanthanum (La), yttrium (Y), strontium (Sr), gadolinium (Gd) ) and aluminum (Al) at least one element.
  • the first electrode, the ferroelectric layer and the second electrode are stacked in a vertical direction, that is, the first electrode may be the bottom electrode and the second electrode may be the top electrode.
  • the first electrode, the ferroelectric layer and the second electrode can also be arranged side by side in the horizontal direction.
  • the first electrode, the ferroelectric layer and the second electrode can also be arranged sequentially from the inside to the outside, that is, the ferroelectric layer surrounds the first electrode.
  • the electrode design, the second electrode is arranged around the ferroelectric layer, is not limited here.
  • the stacked HfO 2 -based ferroelectric material layer and the oxide material layer with a layered structure refer to being stacked in the direction in which the first electrode points to the second electrode.
  • the first electrode points to the second electrode.
  • the direction of the electrode is the vertical direction
  • the HfO 2 -based ferroelectric material layer and the oxide material layer with a layered structure are stacked in the vertical direction.
  • the direction of the first electrode pointing to the second electrode is the horizontal direction
  • the HfO 2- based ferroelectric material layer The layers and the oxide material layers with a layered structure are stacked in the horizontal direction.
  • ferroelectric memory cell in this application is suitable for the MIM capacitor structure with any electrode combination.
  • the first electrode and the second electrode can be arranged symmetrically, and the first electrode and the second electrode can also be arranged asymmetrically, which will not be discussed here. limited.
  • this application does not limit the materials of the first electrode and the second electrode.
  • They may be conductive nitride materials, such as titanium nitride (TiN), tantalum nitride (TaN), etc., or they may be metal materials, such as Tungsten (W), ruthenium (Ru), molybdenum (Mo), iridium (Ir), nickel (Ni), platinum (Pt), etc.
  • conductive metal oxide materials such as ruthenium oxide (RuO), iridium oxide ( IrO), indium tin oxide (ITO), niobate-doped strontium titanate (Nb-STO), lanthanum strontium manganese oxide ((LaSr)MnO 3 ), etc.
  • RuO ruthenium oxide
  • IrO iridium oxide
  • ITO indium tin oxide
  • Nb-STO niobate-doped strontium titanate
  • LaSr lanthanum strontium manganese oxide
  • the oxide material layer 032 can be located between the first electrode 01 and the HfO2- based ferroelectric material layer 031, or, as shown in Figure 3, the oxide material layer 032 can also be Located between the second electrode 02 and the HfO2- based ferroelectric material layer 031, or, as shown in Figure 4, the oxide material layer 032 is located between the first electrode 01 and the HfO2- based ferroelectric material layer 031 and between the second between the electrode 02 and the HfO 2 -based ferroelectric material layer 031, which is beneficial to reducing the oxygen vacancies at the interface between the first electrode and/or the second electrode and the ferroelectric layer.
  • the oxide material layer 032 can also be located between the HfO 2 -based ferroelectric material layers 031 , which is beneficial to reducing oxygen vacancies inside the ferroelectric layer 03 .
  • Figure 5 can also be combined with any one of Figures 2 to 4, that is, on the basis of any structure of Figures 2 to 4, there is also an HfO 2- based ferroelectric material layer 031.
  • An oxide material layer 032 is provided in between.
  • the number of the oxide material layer 032 is not limited. As shown in Figure 5, only One layer of oxide material layer 032, of course, multiple layers of oxide material layer 032 can also be provided. For example, as shown in Figure 7, two layers of oxide material layer 032 are provided between the HfO2- based ferroelectric material layer 031, which will not be discussed here. limited.
  • the oxide material layer with a layered structure may include alternately stacked single atomic layers of oxides of A (AO x ) and perovskite structural layers containing A and B, where A and B are metal elements.
  • the chemical formula of the perovskite structural layer containing A and B is mainly ABO 3 .
  • the single atomic layer of AO x is electrically neutral, it can self-adjust the ion valence state to neutralize charged defects such as space charges or oxygen vacancies.
  • the oxygen ions in the material layer are more active, and the oxygen vacancies are more likely to be transferred to the oxide material layer during the migration process without repeated migration in the HfO 2- based ferroelectric material layer 031, causing fatigue or even forming a conductive path to breakdown the entire device.
  • the Bi-containing oxide material layer can be prepared using the atomic layer deposition (ALD) method, which can be integrated into existing processes, which is beneficial to promotion and application.
  • ALD atomic layer deposition
  • AO x can be Bi 2 O 2-x , 0 ⁇ x ⁇ 2, such as Bi 2 O 2 , Bi 2 O 1.5 , Bi 2 O 1 , Bi 2 O 0.5 , etc.
  • the chemical formula of the oxide material in the oxide material layer with a layered structure may be Bi 2 WO 6 , Bi 2 Ti 3 O 12 or CaBi 4 Ti 4 O 12 , etc., which is not limited here.
  • the schematic diagram of the crystal structure of Bi 2 WO 6 is shown in Figure 8
  • the schematic diagram of the crystal structure of Bi 2 Ti 3 O 12 is shown in Figure 9
  • the schematic diagram of the crystal structure of CaBi 4 Ti 4 O 12 is shown in Figure 10 .
  • the Bi 2 O 2 single atomic layer can increase the interlayer lattice spacing between the perovskite structure layers, making it easier for oxygen ions to move in the material, so the oxygen ions in it It is easier to enter the interface with the electrode or the HfO 2 -based ferroelectric material layer 031 to achieve the purpose of compensating for the oxygen vacancies therein.
  • the oxide material layer having a layered structure may include a layered oxide having a Ruddlesden-Popper phase structure.
  • layered oxides with a Ruddlesden-Popper phase structure are mainly composed of two-dimensional perovskite-like layers interlaced with cations.
  • the general formula of layered oxides with Ruddlesden-Popper phase structure is generally A n+ 1 B n The number of layers.
  • the Ruddlesden-Popper phase structure is a phase structure formed by the symbiosis of a perovskite type structure and a NaCl type structure.
  • a and B are transition metal elements, and X is an oxygen ion.
  • oxygen ions move easily between the two-dimensional perovskite-like layers.
  • transition metal ions with variable valence states when oxygen vacancies exist, they can be neutralized by regulating the valence state of the metal ions. Therefore, the layered oxide with the Ruddlesden-Popper phase structure can provide sufficient oxygen ions for the ferroelectric layer to reduce the oxygen vacancy concentration, thereby weakening the negative effects of oxygen vacancies on awakening, fatigue and breakdown, and ultimately improving the electrical performance of the device. and durability purposes.
  • A in a layered oxide with a Ruddlesden-Popper phase structure, A can be Sr, B Can be Ru, X is O.
  • n the chemical formula of the layered oxide with the Ruddlesden-Popper phase structure is Sr 2 Ru 1 O 4 , and the schematic diagram of the crystal structure of Sr 2 Ru 1 O 4 is shown in Figure 11 .
  • this application also provides a ferroelectric material with a layered structure.
  • the ferroelectric material is mainly composed of HfO 2 -based ferroelectric material unit cell layers and Bi oxide-containing atomic layers alternately stacked.
  • an atomic layer of Bi-containing oxide layer can be inserted after each layer of HfO 2 -based ferroelectric material unit cell layer is formed, thereby forming a layered structure.
  • HfO2- based ferroelectric materials when preparing a HfO 2 -based ferroelectric material thin film, an atomic layer of Bi-containing oxide layer can be inserted after each layer of HfO 2 -based ferroelectric material unit cell layer is formed, thereby forming a layered structure.
  • the oxygen vacancy concentration in the ferroelectric layer 03 can be effectively reduced, thereby weakening the negative effects of oxygen vacancies on awakening, fatigue and breakdown, and ultimately improving the electrical performance and durability of the device. Purpose.
  • the Bi-containing oxide is Bi 2 O 2-x , 0 ⁇ x ⁇ 2, such as Bi 2 O 2 , Bi 2 O 1.5 , Bi 2 O 1 , Bi 2 O 0.5 , etc.
  • a Bi 2 O 2 layer is inserted into a HfO 2 -based ferroelectric material film to build an artificial layered structure.
  • an atomic layer of Bi-containing oxide layer can be inserted after each unit cell layer of HfO 2 -based ferroelectric material is formed, thereby forming an HfO 2 -based ferroelectric material with a layered structure.
  • the present application also provides a ferroelectric memory unit. See Figure 13.
  • the ferroelectric memory unit includes a first electrode 01 and a second electrode 02 arranged oppositely, and a ferroelectric memory unit located between the first electrode 01 and the second electrode 02.
  • the ferroelectric layer 03 between them; the ferroelectric layer 03 is mainly formed by the above-mentioned ferroelectric material with a layered structure.
  • the ferroelectric layer 03 may include alternately stacked HfO 2- based ferroelectric material unit cell layers 033 and Bi oxide-containing Atomic Layer034.
  • HfO 2 -based ferroelectric material unit cell layers 033 and Bi oxide-containing atomic layers 034 are formed into an HfO 2 -based ferroelectric material with a layered structure. Due to the existence of Bi-containing layered structure oxides, the oxygen vacancy concentration in the ferroelectric layer 03 can be effectively reduced, thereby weakening the negative effects of oxygen vacancies on awakening, fatigue and breakdown, and ultimately improving the electrical performance and durability of the device. Purpose.
  • the HfO 2 -based ferroelectric material unit cell layer 033 and the Bi oxide-containing atomic layer 034 in the ferroelectric layer 03 can be stacked in the direction from the first electrode to the second electrode.
  • the HfO 2- based ferroelectric material unit cell layer 033, the Bi-containing oxide atomic layer 034, the HfO 2 -based ferroelectric material unit cell layer 033, the Bi-containing oxide atomic layer 034, ... or it can be Bi-containing oxide
  • the atomic layer 034 of the object, the unit cell layer 033 of the HfO 2 -based ferroelectric material, the atomic layer 034 containing Bi oxide, the unit cell layer 033 of the HfO 2- based ferroelectric material, ... are not limited here.
  • the main difference between the ferroelectric memory unit shown in Fig. 13 and the ferroelectric memory unit shown in Figs. 2 to 7 is that the materials of the ferroelectric layer are different.
  • the implementation of the first electrode and the second electrode can refer to the implementation of the ferroelectric memory unit shown in FIGS. 2 to 7 above, and will not be described again here.
  • this application also provides a memory including a plurality of ferroelectric storage units and a control circuit electrically connected to each ferroelectric storage unit. Specifically, a voltage can be applied to the first electrode and the second electrode of the ferroelectric memory unit through a control circuit to control the ferroelectric memory unit to implement read and write operations.
  • the ferroelectric memory unit may be the ferroelectric memory unit provided in any of the above embodiments of the present application.
  • this application also provides an electronic device, including a processor and a memory coupled to the processor.
  • the electronic device may be a mobile phone, a tablet computer, a notebook computer, a wearable device, a vehicle-mounted device and other electronic devices, and of course it may also be other electronic devices, which are not limited here.

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Abstract

本申请公开了一种铁电材料、铁电存储单元、存储器及电子设备，其中，该铁电存储单元包括相对设置的第一电极和第二电极，以及位于第一电极和第二电极之间的铁电层，铁电层包括层叠设置的HfO2基铁电材料层和具有层状结构的氧化物材料层。从而利用氧化物材料的层状结构使氧化物材料层的晶格间距变大，使氧离子更加容易在材料中移动，从而氧离子更容易进入HfO2基铁电材料中，这样不仅可以在铁电存储单元初始状态下降低界面氧空位对铁电畴的钉扎作用、降低唤醒效应；在极化翻转过程中，氧空位在迁移过程中更容易转移到层状结构中而不会在HfO2基铁电材料中反复迁移造成疲劳甚至形成导电通路使整个器件击穿。

Description

一种铁电材料、铁电存储单元、存储器及电子设备
相关申请的交叉引用
本申请要求在2022年03月22日提交中国专利局、申请号为202210284945.5、申请名称为“一种铁电材料、铁电存储单元、存储器及电子设备”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及存储技术领域，尤其涉及一种铁电材料、铁电存储单元、存储器及电子设备。
背景技术
大数据、互联网及物联网的飞速发展产生了海量数据，进而对数据存储器件的性能提出了更高的要求。在冯诺依曼架构下，计算机中的存储器可分为与计算单元频繁交换数据的内存(例如动态随机存储器(Dynamic Random Access Memory，DRAM))和远离计算单元的外部存储(例如NAND闪存)。DRAM具有高速读写的特点，但为易失性且需要频繁刷写来保持数据。NAND闪存虽然具有非易失性，但读写速度低，可擦写次数低。因此，在当前背景下，寻找同时具有非易失、高读写速度、低功耗的新型存储器件十分迫切且至关重要。
铁电随机存储器(Ferroelectric Random Access Memory，FeRAM)作为一种新型的存储器件，其核心是由金属-铁电材料-金属组成的一个金属(metal)-绝缘体(insulator)-金属(metal)的MIM电容器结构，其原理是利用铁电材料电极化的取向可以被外电场改变的物理现象。当铁电材料作为MFM电容器的绝缘介质材料，由于内部电偶极子的取向会受电场影响而改变，进而会引起电容充放电，在感测放大器的作用下，这些微观物理现象能被识别从而实现“0”或“1”的存储状态。由于FeRAM在外加电场撤去后极化状态仍能保持，因此FeRARM具有非易失的特点。此外，铁电极化翻转主要来源于离子位移，由于翻转速度快且产生焦耳热较小，还具有读写速度快和低功耗的优势。
对于FeRAM中的铁电材料，目前主要采用的锆酸铅(PbZrO3)和钛酸铅(PbTiO3)的混合物Pb(Zr，Ti)O3、钛酸钡(BaTiO3)等钙钛矿结构材料。但由于临界厚度的存在，这类铁电材料需要在一定厚度之上才能展现较稳定的铁电性，因此无法在先进制程的器件中使用，严重限制了其进一步的发展及应用。掺杂锆(Zr)元素的氧化铪(HfO2)(即铪锆氧(HZO))基材料自从被发现具有铁电性以来就受到广泛关注，其铁电性来源于晶格中氧离子的定向位移。此外，因为HZO基的铁电材料与互补金属氧化物半导体(Complementary Metal Oxide Semiconductor，CMOS)工艺兼容且铁电性在10nm下仍能保持，所以有望运用在新型存储器件中并取代DRAM，实现高密度、高速和低功耗。
但是HZO基的铁电材料仍有若干不足，需要进一步改善来提升其耐久性，特别是金属电极和铁电材料界面的缺陷，例如氧空位，会导致HZO基铁电材料中的觉醒、疲劳和击穿效应。这是因为制备过程中存在于金属电极和铁电材料界面的氧空位对铁电畴具有钉 扎作用，抑制初始剩余极化强度Pr。氧空位的钉扎效应随着翻转次数增多而减弱，因此极化强度Pr逐渐增大。进一步进行极化翻转时，氧空位会促使非铁电相(M相)转换为铁电相(O相)，极化强度Pr进一步增大。但极化翻转过程中HZO中的氧离子逐渐脱出聚集在界面，使极化强度Pr开始降低，即疲劳效应。最后大量的氧空位形成导电通道导致器件击穿。因此，如何降低氧空位浓度是本领域技术人员亟需解决的技术问题。
发明内容
有鉴于此，本申请提供了一种铁电材料、铁电存储单元、存储器及电子设备，用于降低铁电存储单元中的氧空位浓度。
第一方面，本申请提供的一种铁电存储单元，包括相对设置的第一电极和第二电极，以及位于第一电极和第二电极之间的铁电层，铁电层可以包括层叠设置的HfO2基铁电材料层和具有层状结构的氧化物材料层。利用氧化物材料的层状结构使氧化物材料层032的晶格间距变大，使氧离子更加容易在材料中移动，从而氧离子更容易进入HfO2基铁电材料中，这样不仅可以在铁电存储单元初始状态下降低界面氧空位对铁电畴的钉扎作用、降低唤醒效应；在极化翻转过程中，氧空位在迁移过程中更容易转移到层状结构中而不会在HfO2基铁电材料中反复迁移造成疲劳甚至形成导电通路使整个器件击穿。因此，本申请提供的铁电存储单元利用铁电层中的层状结构可以有效降低铁电层内部的氧空位浓度，从而减小氧空位积累形成导电通路的可能性，有效调控铁电层的氧空位，进而减弱氧空位对觉醒、疲劳和击穿的负面影响，最终达到提高器件电性能和耐久性的目的。
在本申请中，HfO2基铁电材料包括但不限于在HfO2材料中掺杂锆(Zr)、硅(Si)、镧(La)、钇(Y)、锶(Sr)、钆(Gd)和铝(Al)中至少一种元素。
在具体实施时，第一电极、铁电层和第二电极沿垂直方向层叠设置，即第一电极可以为底电极，第二电极为顶电极。或者，第一电极、铁电层和第二电极也可以沿水平方向并排设置，当然也可以是第一电极、铁电层和第二电极由内向外依次环绕设置，即铁电层环绕第一电极设计，第二电极环绕铁电层设置，在此不作限定。
需要说明的是，本申请中，层叠设置的HfO2基铁电材料层和具有层状结构的氧化物材料层是指沿第一电极指向第二电极方向层叠设置，例如第一电极指向第二电极的方向为垂直方向，HfO2基铁电材料层和具有层状结构的氧化物材料层则沿垂直方向层叠，例如第一电极指向第二电极的方向为水平方向，HfO2基铁电材料层和具有层状结构的氧化物材料层则沿水平方向层叠。
在具体实施时，本申请对第一电极和第二电极的材料不作限定，可以是导电氮化物材料，例如氮化钛(TiN)、氮化钽(TaN)等，也可以是金属材料，例如钨(W)、钌(Ru)、钼(Mo)、铱(Ir)、镍(Ni)、铂(Pt)等，还可以是导电金属氧化物材料，例如氧化钌(RuO)、氧化铱(IrO)、氧化铟锡(ITO)、掺铌钛酸锶(Nb-STO)、镧锶锰氧((LaSr)MnO3)等。
在具体实施时，该氧化物材料层可以位于第一电极与HfO2基铁电材料层之间，或者，氧化物材料层也可以位于第二电极与HfO2基铁电材料层之间，或者，氧化物材料层位于第一电极与HfO2基铁电材料层之间以及位于第二电极与HfO2基铁电材料层之间，这样有利于降低第一电极和/或第二电极与铁电层界面的氧空位。或者，氧化物材料层也可以位于HfO2基铁电材料层之间，这样有利于降低铁电层内部的氧空位。
当然，在本申请中，当在第一电极和/或第二电极与HfO2基铁电材料层之间设置氧化 物材料层时，还可以在HfO2基铁电材料层之间氧化物材料层。例如，第一电极与HfO2基铁电材料层之间有氧化物材料层，在第二电极与HfO2基铁电材料层之间有氧化物材料层，在HfO2基铁电材料层之间有氧化物材料层。
在具体实施，在本申请中，当在HfO2基铁电材料层之间设置氧化物材料层时，对氧化物材料层的层数不作限定，可以仅设置一层氧化物材料层，当然也可以设置多层氧化物材料层，例如，可以在HfO2基铁电材料层之间设置有两层氧化物材料层，在此不作限定。
在本申请中，具有层状结构的氧化物材料层主要由A的氧化物(AOx)单原子层和含A和B的钙钛矿结构层交替层叠组成，其中，A和B均为金属元素，含A和B的钙钛矿结构层的化学式主要是ABO3。在氧化物材料层中，由于单原子层的AOx具有电中性，因此可自我调节离子价态达到中和空间电荷或氧空位等带电缺陷的目的。此外，AOx单原子层可以使钙钛矿结构层之间的层间晶格间距变大，从而使氧离子更加容易在材料中移动，所以其中的氧离子更容易进入与电极之间的界面或HfO2基铁电材料层中，这样不仅可以在铁电存储单元的初始状态下降低界面氧空位对铁电畴的钉扎作用、降低唤醒效应；而且在极化翻转过程中，由于氧化物材料层中氧离子活性更高，氧空位在迁移过程中更容易转移到氧化物材料层中而不会在HfO2基铁电材料层中反复迁移造成疲劳甚至形成导电通路使整个器件击穿。
考虑到Bi的氧化物具有优异的调控缺陷的能力，因此，可选的，在本申请中A为Bi元素。在具体实施时，含Bi的氧化物材料层可以采用原子层沉积(Atomic layer deposition，ALD)法进行制备，可以融合到现有的工艺中，有利于推广和应用。
示例性的，在本申请中AOx可以为Bi2O2-x，0≤x＜2，例如Bi2O2、Bi2O1.5、Bi2O1、Bi2O0.5等。
进一步，在本申请中，具有层状结构的氧化物材料层中氧化物材料的化学式可以为Bi2WO6、Bi2Ti3O12或CaBi4Ti4O12等，在此不作限定。
在另一种可行的实施方式中，具有层状结构的氧化物材料层可以包括具有Ruddlesden-Popper相结构的层状氧化物。其中，具有Ruddlesden-Popper相结构的层状氧化物主要由二维类钙钛矿层与阳离子交错组成。而具有Ruddlesden-Popper相结构的层状氧化物的通式一般为An+1BnX3n+1，其中A和B为阳离子，X为阴离子，n为二维类钙钛矿层中八面体层的数量。通常Ruddlesden-Popper相结构是由钙钛矿型结构和NaCl型结构共生形成的相结构。
示例性的，A和B为过渡金属元素，X为氧离子。由于Ruddlesden-Popper相结构的层状氧化物的层状性质，二维类钙钛矿层之间的氧离子容易移动。并且，由于具有可变价态的过渡金属离子，当存在氧空位时可以通过调控金属离子价态将其中和。因此，具有Ruddlesden-Popper相结构的层状氧化物可以为铁电层提供充足的氧离子来降低氧空位浓度，进而减弱氧空位对觉醒、疲劳和击穿的负面影响，最终达到提高器件电性能和耐久性的目的。
在一种实施例中，在具有Ruddlesden-Popper相结构的层状氧化物中，A可以为Sr，B可以为Ru，X为O，当n＝1时，具有Ruddlesden-Popper相结构的层状氧化物的化学式为Sr2Ru1O4，当n＝2时，具有Ruddlesden-Popper相结构的层状氧化物的化学式为Sr3Ru2O7。
在又一种可行的实施方式中，铁电层包括具有层状结构的HfO2基铁电材料。示例性的，具有层状结构的HfO2基铁电材料可以由HfO2基铁电材料晶胞层和含Bi氧化物的原 子层交替层叠组成。在具体实施时，在制备HfO2基铁电材料薄膜时，可以在每形成一层HfO2基铁电材料晶胞层后插入一个原子层的含Bi氧化物层，从而形成具有层状结构的HfO2基铁电材料。由于含Bi层状结构氧化物的存在，可以有效地降低铁电层中的氧空位浓度，进而减弱氧空位对觉醒、疲劳和击穿的负面影响，最终达到提高器件电性能和耐久性的目的。
在本申请中，含Bi氧化物中还可以掺杂有其它金属元素，在此不作限定。示例性的，本申请中含Bi氧化物为Bi2O2-x，0≤x＜2，例如Bi2O2、Bi2O1.5、Bi2O1、Bi2O0.5等。
第二方面，本申请实施例还提供了一种铁电材料，该铁电材料主要由HfO2基铁电材料晶胞层和含Bi氧化物的原子层交替层叠组成。在具体实施时，在制备HfO2基铁电材料薄膜时，可以在每形成一层HfO2基铁电材料晶胞层后插入一个原子层的含Bi氧化物层，从而形成具有层状结构的HfO2基铁电材料。由于含Bi层状结构氧化物的存在，可以有效地降低铁电层03中的氧空位浓度，进而减弱氧空位对觉醒、疲劳和击穿的负面影响，最终达到提高器件电性能和耐久性的目的。
示例性的，该含Bi氧化物为Bi2O2-x，0≤x＜2，例如Bi2O2、Bi2O1.5、Bi2O1、Bi2O0.5等。利用ALD技术能够精确控制原子层级别生长的优点，将Bi2O2层插入HfO2基铁电材料薄膜中构建人工层状结构。在具体实施时，在制备时，可以在每形成一层HfO2基铁电材料晶胞层后插入一个原子层的含Bi氧化物层，从而形成具有层状结构的HfO2基铁电材料。
第三方面，本申请实施例还提供的一种铁电存储单元，该铁电存储单元包括相对设置的第一电极和第二电极，以及位于第一电极和第二电极之间的铁电层；铁电层主要由第一方面或第一方面的各种实施方式所述的铁电材料形成。该铁电层可以包括交替层叠的HfO2基铁电材料晶胞层和含Bi氧化物的原子层。在该铁电存储单元中，交替层叠的HfO2基铁电材料晶胞层和含Bi氧化物的原子层形成为具有层状结构的HfO2基铁电材料。由于含Bi层状结构氧化物的存在，因此可以有效地降低铁电层中的氧空位浓度，进而减弱氧空位对觉醒、疲劳和击穿的负面影响，最终达到提高器件电性能和耐久性的目的。
第四方面，本申请实施例还提供了一种存储器，包括控制电路和多个如第一方面或第一方面的各种实施方式所述的铁电存储单元，或者，包括控制电路和多个如第三方面或第三方面的各种实施方式所述的铁电存储单元。该控制电路与各铁电存储单元电连接。具体地，可以通过控制电路向铁电存储单元的第一电极和第二电极施加电压，以控制铁电存储单元实现读写操作。
第五方面，本申请实施例还提供了一种电子设备，包括处理器，以及与该处理器耦合的、如第四方面的实施方式所提供的存储器。该电子设备可以是手机、平板电脑、笔记本电脑、可穿戴设备、车载设备等电子设备，当然也可以是其他电子设备，在此不作限定。
上述第四方面和第五方面可以达到的技术效果可以参照上述第一方面至第三方面中任一可能设计可以达到的技术效果说明，这里不再重复赘述。
附图说明
图1为本申请实施例提供的一种铁电存储单元的结构示意图；
图2为本申请实施例提供的一种铁电存储单元的剖面结构示意图；
图3为本申请实施例提供的另一种铁电存储单元的剖面结构示意图；
图4为本申请实施例提供的又一种铁电存储单元的剖面结构示意图；
图5为本申请实施例提供的又一种铁电存储单元的剖面结构示意图；
图6为本申请实施例提供的又一种铁电存储单元的剖面结构示意图；
图7为本申请实施例提供的又一种铁电存储单元的剖面结构示意图；
图8为本申请实施例提供的一种具有层状结构的氧化物材料的晶体结构示意图；
图9为本申请实施例提供的另一种具有层状结构的氧化物材料的晶体结构示意图；
图10为本申请实施例提供的又一种具有层状结构的氧化物材料的晶体结构示意图；
图11为本申请实施例提供的一种具有Ruddlesden-Popper相结构的层状氧化物的晶体结构示意图；
图12为本申请实施例提供的另一种具有Ruddlesden-Popper相结构的层状氧化物的晶体结构示意图；
图13为本申请实施例提供的又一种铁电存储单元的剖面结构示意图。
附图标记说明：
01          第一电极；
02          第二电极；
03          铁电层；
031         HfO2基铁电材料层；
032         氧化物材料层；
033         HfO2基铁电材料晶胞层；
034        含Bi氧化物的原子层。
具体实施方式
为了使本申请的目的、技术方案和优点更加清楚，下面将结合附图对本申请作进一步地详细描述。
应注意的是，在本说明书中，相似的标号和字母在下面的附图中表示类似项，因此，一旦某一项在一个附图中被定义，则在随后的附图中不需要对其进行进一步定义和解释。
在本申请的描述中，需要说明的是，术语“中”、“上”、“下”、“左”、“右”、“竖直”、“水平”、“内”、“外”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本申请和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请的限制。本申请中所描述的表达位置与方向的词，均是以附图为例进行的说明，但根据需要也可以做出改变，所做改变均包含在本发明保护范围内。本申请的附图仅用于示意相对位置关系不代表真实比例。此外，术语“第一”、“第二”仅用于描述目的，而不能理解为指示或暗示相对重要性。
为了方便理解本申请实施例提供的技术方案，下面介绍一下其应用场景。存储单元是存储器中具有数据存储和读写功能的最小单元，可以用于存储一个最小信息单位，即1比特数据(例如0或1)，也就是一个二进制位。通过多个存储单元，可以实现多个二进制位数据的存储。具体地，本申请实施例中，一个存储单元用于存储一个二进制位。本申请提供的存储器可用于手机、平板电脑、笔记本电脑、可穿戴设备、车载设备等电子设备中的数据存储，当然也可以应用于其他电子设备，在此不作限定。
下面结合附图来说明本申请技术方案中的铁电材料、铁电存储单元、存储器及电子设 备。
参见图1，图1为本申请实施例提供的一种铁电存储单元的结构示意图。如图1所示，铁电存储单元包括相对设置的第一电极01和第二电极02，以及位于第一电极01和第二电极02之间的铁电层03。
示例性的，如图2至图5所示，铁电层03可以包括层叠设置的HfO2基铁电材料层031和具有层状结构的氧化物材料层032。利用氧化物材料的层状结构使氧化物材料层032的晶格间距变大，使氧离子更加容易在材料中移动，从而氧离子更容易进入HfO2基铁电材料中，这样不仅可以在铁电存储单元初始状态下降低界面氧空位对铁电畴的钉扎作用、降低唤醒效应；在极化翻转过程中，氧空位在迁移过程中更容易转移到层状结构中而不会在HfO2基铁电材料中反复迁移造成疲劳甚至形成导电通路使整个器件击穿。因此，本申请提供的铁电存储单元利用铁电层中的层状结构可以有效降低铁电层内部的氧空位浓度，从而减小氧空位积累形成导电通路的可能性，有效调控铁电层的氧空位，进而减弱氧空位对觉醒、疲劳和击穿的负面影响，最终达到提高器件电性能和耐久性的目的。
在本申请中，HfO2基铁电材料包括但不限于在HfO2材料中掺杂锆(Zr)、硅(Si)、镧(La)、钇(Y)、锶(Sr)、钆(Gd)和铝(Al)中至少一种元素。
在具体实施时，第一电极、铁电层和第二电极沿垂直方向层叠设置，即第一电极可以为底电极，第二电极为顶电极。或者，第一电极、铁电层和第二电极也可以沿水平方向并排设置，当然也可以是第一电极、铁电层和第二电极由内向外依次环绕设置，即铁电层环绕第一电极设计，第二电极环绕铁电层设置，在此不作限定。
需要说明的是，本申请中，层叠设置的HfO2基铁电材料层和具有层状结构的氧化物材料层是指沿第一电极指向第二电极方向层叠设置，例如第一电极指向第二电极的方向为垂直方向，HfO2基铁电材料层和具有层状结构的氧化物材料层则沿垂直方向层叠，例如第一电极指向第二电极的方向为水平方向，HfO2基铁电材料层和具有层状结构的氧化物材料层则沿水平方向层叠。
进一步地，本申请中的铁电存储单适合任意电极组合的MIM电容器结构，第一电极和第二电极可以是对称设置，第一电极和第二电极也可以是不对称的设置，在此不作限定。
在具体实施时，本申请对第一电极和第二电极的材料不作限定，可以是导电氮化物材料，例如氮化钛(TiN)、氮化钽(TaN)等，也可以是金属材料，例如钨(W)、钌(Ru)、钼(Mo)、铱(Ir)、镍(Ni)、铂(Pt)等，还可以是导电金属氧化物材料，例如氧化钌(RuO)、氧化铱(IrO)、氧化铟锡(ITO)、掺铌钛酸锶(Nb-STO)、镧锶锰氧((LaSr)MnO3)等。
在具体实施时，如图2所示，该氧化物材料层032可以位于第一电极01与HfO2基铁电材料层031之间，或者，如图3所示，氧化物材料层032也可以位于第二电极02与HfO2基铁电材料层031之间，或者，如图4所示，氧化物材料层032位于第一电极01与HfO2基铁电材料层031之间以及位于第二电极02与HfO2基铁电材料层031之间，这样有利于降低第一电极和/或第二电极与铁电层界面的氧空位。或者，如图5所示，氧化物材料层032也可以位于HfO2基铁电材料层031之间，这样有利于降低铁电层03内部的氧空位。
当然，在本申请中，也可以将图5与图2至图4中任一种结合，即在图2至图4的任一结构的基础上，还在HfO2基铁电材料层031之间设置氧化物材料层032。例如图6所示，第一电极01与HfO2基铁电材料层031之间有氧化物材料层032，在第二电极02与HfO2基铁电材料层031之间有氧化物材料层032，在HfO2基铁电材料层031之间有氧化物材料 层032。
在具体实施，在本申请中，当在HfO2基铁电材料层031之间设置氧化物材料层032时，对氧化物材料层032的层数不作限定，如图5所示，可以仅设置一层氧化物材料层032，当然也可以设置多层氧化物材料层032，例如图7所示，在HfO2基铁电材料层031之间设置有两层氧化物材料层032，在此不作限定。
在本申请中，具有层状结构的氧化物材料层可以包括交替层叠的A的氧化物(AOx)单原子层和含A和B的钙钛矿结构层，其中，A和B为金属元素，含A和B的钙钛矿结构层的化学式主要是ABO3。在氧化物材料层中，由于单原子层的AOx具有电中性，因此可自我调节离子价态达到中和空间电荷或氧空位等带电缺陷的目的。此外，AOx单原子层可以使钙钛矿结构层之间的层间晶格间距变大，从而使氧离子更加容易在材料中移动，所以其中的氧离子更容易进入与电极之间的界面或HfO2基铁电材料层031中，这样不仅可以在铁电存储单元的初始状态下降低界面氧空位对铁电畴的钉扎作用、降低唤醒效应；而且在极化翻转过程中，由于氧化物材料层中氧离子活性更高，氧空位在迁移过程中更容易转移到氧化物材料层中而不会在HfO2基铁电材料层031中反复迁移造成疲劳甚至形成导电通路使整个器件击穿。
考虑到Bi的氧化物具有优异的调控缺陷的能力，因此，可选的，在本申请中A为Bi元素。在具体实施时，含Bi的氧化物材料层可以采用原子层沉积(Atomic layer deposition，ALD)法进行制备，可以融合到现有的工艺中，有利于推广和应用。
示例性的，在本申请中AOx可以为Bi2O2-x，0≤x＜2，例如Bi2O2、Bi2O1.5、Bi2O1、Bi2O0.5等。
进一步，在本申请中，具有层状结构的氧化物材料层中氧化物材料的化学式可以为Bi2WO6、Bi2Ti3O12或CaBi4Ti4O12等，在此不作限定。
示例性的，Bi2WO6的晶体结构示意图如图8所示，Bi2Ti3O12的晶体结构示意图如图9所示，CaBi4Ti4O12的晶体结构示意图如图10所示。由图8至图10可以看出，Bi2O2单原子层可以使钙钛矿结构层之间的层间晶格间距变大，从而使氧离子更加容易在材料中移动，所以其中的氧离子更容易进入与电极之间的界面或HfO2基铁电材料层031中，达到补偿其中氧空位的目的。
在另一种可行的实施方式中，具有层状结构的氧化物材料层可以包括具有Ruddlesden-Popper相结构的层状氧化物。其中，具有Ruddlesden-Popper相结构的层状氧化物主要由二维类钙钛矿层与阳离子交错组成。而具有Ruddlesden-Popper相结构的层状氧化物的通式一般为An+1BnX3n+1，其中A和B为阳离子，X为阴离子，n为二维类钙钛矿层中八面体层的数量。通常Ruddlesden-Popper相结构是由钙钛矿型结构和NaCl型结构共生形成的相结构。
示例性的，A和B为过渡金属元素，X为氧离子。由于Ruddlesden-Popper相结构的层状氧化物的层状性质，二维类钙钛矿层之间的氧离子容易移动。并且，由于具有可变价态的过渡金属离子，当存在氧空位时可以通过调控金属离子价态将其中和。因此，具有Ruddlesden-Popper相结构的层状氧化物可以为铁电层提供充足的氧离子来降低氧空位浓度，进而减弱氧空位对觉醒、疲劳和击穿的负面影响，最终达到提高器件电性能和耐久性的目的。
在一种实施例中，在具有Ruddlesden-Popper相结构的层状氧化物中，A可以为Sr，B 可以为Ru，X为O。示例性的，当n＝1时，具有Ruddlesden-Popper相结构的层状氧化物的化学式为Sr2Ru1O4，Sr2Ru1O4的晶体结构示意图如图11所示。当n＝2时，具有Ruddlesden-Popper相结构的层状氧化物的化学式为Sr3Ru2O7，Sr3Ru2O7的晶体结构示意图如图12所示。由图11和图12可以看出，由于Ruddlesden-Popper相结构的层状氧化物的层状结构，因此二维类钙钛矿层之间的氧离子容易移动，氧离子更容易进入与电极之间的界面或HfO2基铁电材料层031中，从而达到补偿其中氧空位的目的。
基于同一技术构思，本申请还提供了一种具有层状结构的铁电材料，该铁电材料主要由HfO2基铁电材料晶胞层和含Bi氧化物的原子层交替层叠组成。在具体实施时，在制备HfO2基铁电材料薄膜时，可以在每形成一层HfO2基铁电材料晶胞层后插入一个原子层的含Bi氧化物层，从而形成具有层状结构的HfO2基铁电材料。由于含Bi层状结构氧化物的存在，可以有效地降低铁电层03中的氧空位浓度，进而减弱氧空位对觉醒、疲劳和击穿的负面影响，最终达到提高器件电性能和耐久性的目的。
示例性的，该含Bi氧化物为Bi2O2-x，0≤x＜2，例如Bi2O2、Bi2O1.5、Bi2O1、Bi2O0.5等。利用ALD技术能够精确控制原子层级别生长的优点，将Bi2O2层插入HfO2基铁电材料薄膜中构建人工层状结构。在具体实施时，在制备时，可以在每形成一层HfO2基铁电材料晶胞层后插入一个原子层的含Bi氧化物层，从而形成具有层状结构的HfO2基铁电材料。
相应地，本申请还提供了一种铁电存储单元，参见图13，该铁电存储单元包括相对设置的第一电极01和第二电极02，以及位于第一电极01和第二电极02之间的铁电层03；铁电层03主要由上述具有层状结构的铁电材料形成，该铁电层03可以包括交替层叠的HfO2基铁电材料晶胞层033和含Bi氧化物的原子层034。在该铁电存储单元中，交替层叠的HfO2基铁电材料晶胞层033和含Bi氧化物的原子层034形成为具有层状结构的HfO2基铁电材料。由于含Bi层状结构氧化物的存在，可以有效地降低铁电层03中的氧空位浓度，进而减弱氧空位对觉醒、疲劳和击穿的负面影响，最终达到提高器件电性能和耐久性的目的。
需要说明是，在该实施例中，该铁电层03中的HfO2基铁电材料晶胞层033和含Bi氧化物的原子层034可以沿第一电极指向第二电极方向层叠，具体可以是HfO2基铁电材料晶胞层033、含Bi氧化物的原子层034、HfO2基铁电材料晶胞层033、含Bi氧化物的原子层034、……，也可以是含Bi氧化物的原子层034、HfO2基铁电材料晶胞层033、含Bi氧化物的原子层034、HfO2基铁电材料晶胞层033、……，在此不作限定。
可以理解的是，图13所示的铁电存储单元与图2至图7所示铁电存储单元的主要区别在于铁电层的材料不相同，对于图13所示的铁电存储单元中第一电极、第二电极的实施可以参见上述图2至图7所示铁电存储单元的实施，在此不再赘述。
相应地，本申请还提供了一种存储器，包括多个铁电存储单元和与各铁电存储单元电连接的控制电路。具体地，可以通过控制电路向铁电存储单元的第一电极和第二电极施加电压，以控制铁电存储单元实现读写操作。该铁电存储单元可以是本申请上述任一种实施例提供的铁电存储单元。
相应地，本申请还提供了一种电子设备，包括处理器和与处理器耦合的存储器。该电子设备可以是手机、平板电脑、笔记本电脑、可穿戴设备、车载设备等电子设备，当然也可以是其他电子设备，在此不作限定。
显然，本领域的技术人员可以对本申请进行各种改动和变型而不脱离本申请的精神和范围。这样，倘若本申请的这些修改和变型属于本申请权利要求及其等同技术的范围之内，则本申请也意图包含这些改动和变型在内。

Claims (13)

  1. 一种铁电存储单元，其特征在于，包括相对设置的第一电极和第二电极，以及位于所述第一电极和第二电极之间的铁电层；其中，
    所述铁电层包括层叠设置的氧化铪基铁电材料层和具有层状结构的氧化物材料层。
  2. 如权利要求1所述的铁电存储单元，其特征在于，所述具有层状结构的氧化物材料层位于所述第一电极与所述氧化铪基铁电材料层之间，和/或位于所述第二电极与所述氧化铪基铁电材料层之间，和/或位于所述氧化铪基铁电材料层之间。
  3. 如权利要求2所述的铁电存储单元，其特征在于，所述具有层状结构的氧化物材料层包括交替层叠设置的A的氧化物单原子层和含A和B的钙钛矿结构层，其中，所述A和所述B均为金属元素。
  4. 如权利要求3所述的铁电存储单元，其特征在于，所述A为Bi元素。
  5. 如权利要求4所述的铁电存储单元，其特征在于，所述具有层状结构的氧化物材料层中氧化物材料的化学式为Bi2WO6、Bi2Ti3O12或CaBi4Ti4O12。
  6. 如权利要求1所述的铁电存储单元，其特征在于，所述具有层状结构的氧化物材料层包括具有Ruddlesden-Popper相结构的层状氧化物，其中，所述具有Ruddlesden-Popper相结构的层状氧化物主要由二维类钙钛矿层与阳离子交错组成。
  7. 如权利要求6所述的铁电存储单元，其特征在于，所述具有Ruddlesden-Popper相结构的层状氧化物的通式为An+1BnX3n+1，其中所述A和所述B为阳离子，所述X为阴离子，所述n为所述二维类钙钛矿层中八面体层的数量。
  8. 如权利要求7所述的铁电存储单元，其特征在于，所述A和所述B为过渡金属元素，所述X为氧元素。
  9. 一种铁电材料，其特征在于，所述铁电材料包括交替层叠的氧化铪基铁电材料晶胞层和含铋氧化物的原子层。
  10. 如权利要求9所述的铁电材料，其特征在于，所述含铋氧化物为Bi2O2-x，0≤x＜2。
  11. 一种铁电存储单元，其特征在于，包括相对设置的第一电极和第二电极，以及位于所述第一电极和第二电极之间的铁电层；其中，所述铁电层包括如权利要求9或10所述的铁电材料。
  12. 一种存储器，其特征在于，包括多个如权利要求1-8、11任一项所述的铁电存储单 元和与各所述铁电存储单元电连接的控制电路。
  13. 一种电子设备，其特征在于，包括处理器，以及与所述处理器耦合的、如权利要求12所述的存储器。
PCT/CN2023/076001 2022-03-22 2023-02-14 一种铁电材料、铁电存储单元、存储器及电子设备 WO2023179250A1 (zh)

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